Optoelectronic component and package for an optoelectronic component

ABSTRACT

Optoelectronic components with a semiconductor chip, which is suitable for emitting primary electromagnetic radiation, a basic package body, which has a recess for receiving the semiconductor chip and electrical leads for the external electrical connection of the semiconductor chip, and a chip encapsulating element, which encloses the semiconductor chip in the recess. The basic package body is at least partly optically transmissive at least for part of the primary radiation and an optical axis of the semiconductor chip runs through the basic package body. The basic package body comprises a luminescence conversion material, which is suitable for converting at least part of the primary radiation into secondary radiation with wavelengths that are at least partly changed in comparison with the primary radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/575,797, which has a 35 U.S.C. §371(c) date of Dec. 17, 2007, whichis a 35 U.S.C. §371 national phase application of PCT Application No.PCT/DE2005/001735, filed Sep. 28, 2005, which claims priority to GermanPatent Application No. 10 2004 047 640.3, filed Sep. 30, 2004. Thecontents of each of these applications are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The invention relates to an optoelectronic component and to a packagefor an optoelectronic component.

BACKGROUND OF THE INVENTION

Surface-mountable (SMD) light-emitting diode components (LEDs) inleadframe technology are often mounted in a transfer-moulded orinjection-moulded plastic package body prefabricated on the leadframe,are connected there to electrical leads and, for protection againstharmful external influences, are encapsulated with a transparent castingcompound, through which light is coupled out during the operation of theLEDs.

In particular in the case of so-called conversion LEDs, in which atleast part of the radiation emitted by the semiconductor chip (hereafterprimary radiation) is converted by a luminescent material in the castingcompound into radiation with an at least partly changed wavelength incomparison with the primary radiation, it is technically often difficultto introduce the intended amount of luminescent material at the intendedlocation. Difficulties are caused in particular by a distribution of thewavelength and a distribution of the brightness of semiconductor chipsthat are nominally identical. Among the technical problems that areoften observed are segregation effects of the luminescent material afterapplication of the casting compound to the chip. The aforementionedaspects make a significant contribution to non-uniformities in theradiation characteristic of conventional conversion LEDs and adverselyaffect the yield in mass production.

Known conversion LEDs are described for example in the documents WO97/50132 A1, WO 98/12757 A1 and WO 01/50540 A1.

SUMMARY OF THE INVENTION

It is, in particular, an object of the present invention to provide anoptoelectronic component with which a reproducible radiationcharacteristic can be achieved in mass production by means which aretechnically as simple as possible.

Advantageous embodiments and developments of the optoelectroniccomponent and of the package are specified below.

In one embodiment, a semiconductor chip and a luminescence conversionmaterial are provided, the semiconductor chip being suitable foremitting primary electromagnetic radiation and the luminescenceconversion material being suitable for absorbing at least part of theprimary radiation and emitting secondary radiation with wavelengths thatare at least partly changed in comparison with the primary radiation.

Furthermore, a basic package body is provided, having a recess forreceiving the semiconductor chip and electrical leads for the externalelectrical connection of the semiconductor chip, which on the one handare respectively connected in an electrically conducting manner toelectrical contacts of the semiconductor chip and on the other handrespectively have a terminal area which can be contacted from theoutside.

The semiconductor chip is mounted in the recess and enclosed by a chipencapsulating element, which is intended to protect the semiconductorchip from harmful environmental influences. The semiconductor chip is,for example, advantageously mounted in the recess by means of a siliconeresin compound. The chip encapsulating element may, for example,advantageously comprise a silicone resin compound. Similarly, however,it is conceivable for the chip encapsulating element to comprise amaterial based on epoxy resin and/or PMMA, in order for example toachieve improved protection against mechanical influences. Furthermore,the chip encapsulating element may comprise a material based on an epoxyresin/silicone resin hybrid material, with for example an epoxy resinfraction of 50 percent and a silicone resin fraction of 50 percent.

The basic package body is optically transmissive at least for part ofthe primary radiation and an optical axis of the semiconductor chip runsthrough the basic package body, so that a large part of the primaryradiation emitted by the semiconductor chip is radiated into the basicpackage body. The optical axis is in the present case the central axisof a radiation cone emitted by the semiconductor chip. The term“optically transmissive” broadly covers transparency, translucency,transmissivity with dispersing means and other types of opticaltransmissivity.

The luminescence conversion material is embedded in the basic packagebody and is suitable for converting at least part of the primaryradiation into secondary radiation with wavelengths that are at leastpartly changed in comparison with the primary radiation. Examples ofsuitable luminescence conversion materials are specified in thedocuments WO 97/50132 A1, WO 98/12757 A1 and WO 01/08452 A1, thecontents of their disclosure to this extent hereby being expresslyincorporated by reference.

During the operation of the component, the basic package body emitselectromagnetic radiation which comprises primary radiation passingthrough the basic package body and secondary radiation emitted by theluminescence conversion material.

In the case of an advantageous embodiment of the basic package body, itcomprises a plastic moulding prefabricated by means of aninjection-moulding or transfer-moulding process.

In the case of another advantageous embodiment, the basic package bodycomprises a prefabricated moulding of glass and/or aradiation-transmissive ceramic.

The basic package body advantageously comprises a beam-shaping opticalelement and/or is itself formed as a beam-shaping optical element.

In the case of an advantageous development of the component, the basicpackage body has an outer layer, lying away from the recess, and aninner layer, enclosing the recess, between which layers there is aconverter layer, which contains the luminescence conversion material.

The thickness and/or the form of the converter layer may in this case beformed advantageously in such a way that it is adapted to correspond toa radiation characteristic of the semiconductor chip that is not uniformover a solid radiating angle.

Particularly suitable is a type of design for components in which theprimary radiation comprises ultraviolet radiation and/or shortwave blueradiation.

In the case of a preferred configuration of the component, the basicpackage body is formed on electrical leads of a metallic electricalleadframe which are connected to electrical contact areas of thesemiconductor chip, for example by means of bonding wires.

In the case of a component and a package, the prefabricated basicpackage body is used for coupling out light and not, as in theconventional way, a clearance made in a prefabricated basic package bodyfilled with a clear casting compound. For this purpose, theprefabricated basic package body is produced from an opticallytransmissive compound. Luminescence conversion material can then beintroduced, inter alia, into this compound in a defined amount and form.

The semiconductor chip, which in such a type of design radiates into thebasic package body, is inserted into the recess in the basic packagebody and fastened there. In the case of semiconductor chips which havean electrical contact on the side facing the basic package body, thisadvantageously takes place for example by using a transparent conductiveadhesive. In the case of semiconductor chips which have both contacts onthe side facing away from the basic package body (for examplesemiconductor chips based on a nitride IIIN compound semiconductormaterial with a transparent substrate, for example a sapphiresubstrate), the fastening of the semiconductor chip may take place forexample by means of a silicone resin compound.

The advantage of a silicone resin compound is, in particular, itsstability with respect to UV and/or shortwave blue radiation. In therecess, the semiconductor chip is enclosed from its rear side by acompound which can be optimized with regard to resistance to harmfulenvironmental influences and the optical properties of which areinsignificant.

One particular advantage of the component is that the basic package bodyincluding the luminescence conversion material can be adapted in atechnically comparatively simple way to the given chip characteristicsin each case. There is a possibility of integrating the luminescenceconversion material in the basic package body in a defined form, amountand thickness before the semiconductor chip is fitted. After introducingthe semiconductor chip, the optical properties of the future componentare already fixed, so that the semiconductor chip only has to beelectrically connected to the electrical leads.

The placement accuracy of a semiconductor chip using mounting technologythat is currently available in mass production is of the order ofmagnitude of 40-70 μm down to 5 μm, depending on the insertion rate.This placement accuracy combined with prefabricated optics of theprefabricated basic package body advantageously make very exactlydefined radiation characteristics of LED components possible.

A further significant advantage is that the package concept opens up thepossibility of combining radiation-resistant materials, such as glassfor example, with shortwave emitters, that is semiconductor chipsemitting ultraviolet and/or shortwave blue radiation.

Further advantages, advantageous embodiments and developments of theinvention emerge from the exemplary embodiments described below inconjunction with FIGS. 1 to 4.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional representation of a first exemplaryembodiment,

FIG. 2 shows a schematic sectional representation of a second exemplaryembodiment,

FIG. 3 shows a schematic sectional representation of a third exemplaryembodiment, and

FIG. 4 shows a schematic sectional representation of a fourth exemplaryembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the exemplary embodiments and associated figures, component partsthat are the same or act in the same way are respectively provided withthe same reference numerals. The elements represented in the figures, inparticular the layer thicknesses, are not to be regarded as true toscale. Rather, they may in some cases be exaggerated for betterunderstanding.

In the case of the exemplary embodiment according to FIG. 1, a basicpackage body 3 shaped in a hemispherical manner has a recess 31 on theside of the basic package body 3 facing away from the hemisphericallycurved surface. Embedded in the basic package body 3 is a luminescenceconversion material 5 in the form of a converter layer 51, which runsparallel to the hemispherically curved surface. That is to say that theconverter layer 51 has, for example, the same or substantially the samecurvature as the hemispherically curved surface. On account of itshemispherical form, the package body 3 acts as a beam-focusing opticaloutput coupler.

The basic package body 3 comprises, for example, an injection-moulded ortransfer-moulded prefabricated moulding of a transparent polymermaterial, of glass or of a transparent ceramic material.

The basic package body 3 has an outer layer, lying away from the recess31, and an inner layer, surrounding the recess, between which there isthe converter layer 51, which has the luminescence conversion material5. According to at least one exemplary embodiment, the inner and outerlayers are in this case free from luminescence conversion material.

Examples of suitable luminescence conversion materials are specified inthe documents WO 97/50132 A1, WO 98/12757 A1 and WO 01/08452 A1 and forthis reason are not explained in any more detail at this point.

The recess 31 is made to be of only slightly larger dimensions than theradiation-emitting semiconductor chip 1. For example, the recess 31 ismade to be at most 10 percent larger than the radiation-emittingsemiconductor chip 1. With preference, the recess 31 is made to be atmost 7 percent larger than the radiation-emitting semiconductor chip 1.With particular preference, the recess 31 is made to be at most 2.5percent larger than the radiation-emitting semiconductor chip 1. Forexample, the radiation-emitting semiconductor chip 1 is based on anitride III/V compound semiconductor material and, during its operation,emits, inter alia, ultraviolet and shortwave blue radiation. Forexample, in the case of the radiation-emitting semiconductor chip 1, theelectrical terminal area of the p side and the electrical terminal areaof the n side are arranged on its rear side, facing away from the basicpackage body 3. Such semiconductor chips 1 are known to a person skilledin the art and for this reason are not explained in any more detail atthis point. Such semiconductor chips are described for example in thedocuments EP 599 224 A1 and EP 622 858 A2, the content of theirdisclosure to this extent hereby being expressly incorporated byreference.

The semiconductor chip 1 is fastened in the recess 31 by means of abonding layer 7 of transparent silicone resin in such a way that itemits radiation primarily into the basic package body 3. The opticalaxis 13 of the semiconductor chip 1 runs through the basic package body3.

On the rear side of the basic package body 3, electrical leads 32, 33run from outside the basic package body 3 toward the recess 31, to whichleads electrical contacts 11, 12 of the semiconductor chip 1 areconnected in an electrically conducting manner. This may take place forexample, as represented in FIG. 1, by means of a small carrier plate 8of semiconductor material, which has a p-conductively doped region 81between a p contact area of the semiconductor chip 1 and the leads 32assigned to it and a n-conductively doped region 82 between an n contactarea of the semiconductor chip 1 and the leads 33 assigned to it. Theelectrically conducting connections between the contact areas of thesemiconductor chip 1 and the assigned doped regions 81, 82 of the smallcarrier plate 8 may be established for example by means of ITO and/orelectrically conducting ZnO layers. Layers of other TCO (transparentconductive oxide) materials are also conceivable.

As an alternative, the electrical connections between the contact areasof the semiconductor chip 1 and the leads 32, 33 may be realized forexample by means of bonding wires 2 (cf. FIG. 2) or by means of metalfoils or by using other suitable means.

The electrical leads 32, 33 for the electrical connection of thesemiconductor chip 1 are self-supporting metallic sheet-metal strips,which on the one hand are respectively connected in an electricallyconducting manner to the electrical contacts 11, 12 of the semiconductorchip 1 and on the other hand respectively have a terminal area 34, 35which can be contacted from the outside. They are formed outside thebasic package body in such a way, for example in the manner of a rocker,that the component is surface-mountable.

When using a semiconductor chip 1 on which the electrical terminal areasof the n side and of the p side are on opposite main faces of thesemiconductor chip 1, an electrical connecting track, for example ametallic conductor track, is arranged for example in the recess in orderto connect the terminal area facing the basic package body 3 to one ofthe leads 32, 33.

On the rear side of the basic package body 3 there is a plastic mouldingcompound 4, which encapsulates the semiconductor chip 1 including thesmall carrier plate 8, the material of which is based for example onepoxy resin or on PMMA and which may be formed so as to absorb radiationand/or reflect it.

The exemplary embodiment according to FIG. 3 differs from thosepreviously described in particular in that the luminescence conversionmaterial 5 is not embedded in the basic package body 3 but is containedin a converter layer 51 between the semiconductor chip 1 and themoulding of the basic package body 3 in the recess 31. This converterlayer may comprise, for example, a matrix based on silicone resin, inwhich the luminescence conversion material 5 is embedded. Similarly,however, a matrix based on glass or a radiation-transmissive ceramic canalso be used.

As an alternative, as represented in FIG. 4, the inner surfaces of therecess 31 may be coated with luminescence conversion material 5. Aremaining intermediate space between the semiconductor chip 1 and theluminescence conversion material 5 is then preferably filled with atransparent filling compound, such as silicone resin for example.

In the case of all the exemplary embodiments, the thickness and/or theform of the converter layer 51 can be advantageously formed in such away that it is adapted to correspond to a radiation characteristic ofthe semiconductor chip 1 that is not uniform over a solid radiatingangle.

It goes without saying that the invention is not restricted to theexemplary embodiments that are explicitly described. Rather, theinvention also comprises any novel feature and any novel combination offeatures, which includes in particular any combination of featuresrevealed to a person skilled in the art in the various claims, even ifthis combination is not explicitly specified in the patent claims.

1-16. (canceled)
 17. An optoelectronic component with: a semiconductorchip, which is suitable for emitting primary electromagnetic radiation,a basic package body, which has a recess for receiving the semiconductorchip and electrical leads for the external electrical connection of thesemiconductor chip, which are connected in an electrically conductingmanner to electrical contacts of the semiconductor chip and have aterminal area which can be contacted from the outside, and a chipencapsulating element, which encloses the semiconductor chip in therecess, wherein: the basic package body is at least partly opticallytransmissive at least for part of the primary radiation and an opticalaxis of the semiconductor chip runs through the basic package body, suchthat a large part of the primary radiation emitted by the semiconductorchip is radiated into the basic package body, the basic package bodycomprises a luminescence conversion material, which is suitable forconverting at least part of the primary radiation into secondaryradiation with wavelengths that are at least partly changed incomparison with the primary radiation, and during the operation of thecomponent, the basic package body emits radiation which comprisesprimary radiation passing through the basic package body and secondaryradiation emitted by the luminescence conversion material.
 18. Theoptoelectronic component according to claim 17, wherein the luminescenceconversion material is embedded in the basic package body.
 19. Theoptoelectronic component according to claim 17 wherein a converter layeris arranged between the semiconductor chip and the basic package body,said converter layer comprising the luminescence conversion material.20. The optoelectronic component according to claim 19, wherein theconverter layer covers an inner surface of the recess.
 21. Theoptoelectronic component according to claim 17, wherein the basicpackage body comprises a plastic moulding prefabricated by means of aninjection-moulding or transfer-moulding process.
 22. The optoelectroniccomponent according to claim 17, wherein the basic package bodycomprises a prefabricated moulding of glass or radiation-transmissiveceramic.
 23. The optoelectronic component according to claim 17, whereinthe basic package body comprises a beam-shaping optical element.
 24. Theoptoelectronic component according to claim 17, wherein the primaryradiation comprises ultraviolet radiation and/or shortwave blueradiation.
 25. The optoelectronic component according to claim 17,wherein the basic package body has an outer layer, lying away from therecess, and an inner layer, enclosing the recess, between which layersthere is a converter layer, which has the luminescence conversionmaterial.
 26. The optoelectronic component according to claim 25,wherein the outer and inner layers are free from luminescence conversionmaterial.
 27. The optoelectronic component according to claim 17,wherein the thickness and/or the form of the converter layer is formedin such a way that it is adapted to correspond to a radiationcharacteristic of the semiconductor chip that is not uniform over asolid radiating angle.
 28. An optoelectronic component with: asemiconductor chip, which is suitable for emitting primaryelectromagnetic radiation, a basic package body, which has a recess forreceiving the semiconductor chip and electrical leads for the externalelectrical connection of the semiconductor chip, which are connected inan electrically conducting manner to electrical contacts of thesemiconductor chip and respectively have a terminal area which can becontacted from the outside, and a chip encapsulating element, whichencloses the semiconductor chip in the recess, wherein: the basicpackage body is at least partly optically transmissive at least for partof the primary radiation and an optical axis of the semiconductor chipruns through the basic package body, so that a large part of the primaryradiation emitted by the semiconductor chip is radiated into the basicpackage body, the basic package body comprises a luminescence conversionmaterial, which is suitable for converting at least part of the primaryradiation into secondary radiation with wavelengths that are at leastpartly changed in comparison with the primary radiation, during theoperation of the component, the basic package body emits radiation whichcomprises primary radiation passing through the basic package body andsecondary radiation emitted by the luminescence conversion material, andthe luminescence conversion material is embedded in the basic packagebody.
 29. A package for an optoelectronic semiconductor chip which issuitable for emitting primary electromagnetic radiation, with a basicpackage body, which has a recess for receiving the semiconductor chipand electrical leads for the electrical connection of the semiconductorchip, which is at least partly transmissive at least for part of theprimary radiation and wherein there is embedded a luminescenceconversion material, which is suitable for converting at least part ofthe primary radiation into secondary radiation with wavelengths that areat least partly changed in comparison with the primary radiation. 30.The package according to claim 29, wherein the basic package bodycomprises a plastic moulding prefabricated by means of aninjection-moulding or transfer-moulding process.
 31. The packageaccording to claim 30, wherein the plastic moulding is formed on ametallic electrical leadframe.
 32. The package according to claim 29,wherein the basic package body comprises a prefabricated moulding ofglass or radiation-transmissive ceramic.
 33. The package according toclaim 29, wherein the basic package body comprises a beam-shapingoptical element.
 34. The package according to claim 29, wherein thebasic package body has an outer layer, lying away from the recess, andan inner layer, enclosing the recess, between which layers there is aconverter layer, which has the luminescence conversion material.
 35. Thepackage according to claim 34, wherein the outer and inner layers arefree from luminescence conversion material.